https://devzone.nordicsemi.com/f/nordic-q-a/58662/uart-pin-connfigurationHi, I am using nrf52840 DK to create the uart ble app. The starting point is ble_app_uart example from SDK52 15.3. I changed pin configuration for uart so I can have RX and TX pins on one of the external headers. This is the code in the pca10052.h fileen-USTelligent Community 13Wed, 04 Mar 2020 11:55:51 GMThttps://devzone.nordicsemi.com/thread/238008?ContentTypeID=1Wed, 04 Mar 2020 11:55:51 GMT137ad170-7792-4731-bb38-c0d22fbe4515:4dd91cb1-2271-4faf-ab29-d28c36859bcbEdvin<p>The APP_ERROR_HANDLER() or the APP_ERROR_CHECK is good for use during development, or if you want to reset the device when an error occurs. In some cases, you may not care about certain events/return values. In that case it is safe to remove them.</p> <p>Just know that in this case, you will not get an event when you actually have some communication error, but I don&#39;t think that is a common issue when the pins are connected.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/238004?ContentTypeID=1Wed, 04 Mar 2020 11:40:53 GMT137ad170-7792-4731-bb38-c0d22fbe4515:5d931c4d-10d8-456f-b756-44f6795eaaf3Vojislav<p>Commenting out APP_ERROR_HANFLER() worked, thank you.<br /><br />Is this safe for code, or should this state be handled somehow?&nbsp;&nbsp;</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/237962?ContentTypeID=1Wed, 04 Mar 2020 09:24:14 GMT137ad170-7792-4731-bb38-c0d22fbe4515:7105ee4e-cfc5-413a-b115-74972dc9d141Edvin<p>It is probably the UART event handler receiving some communication error. Try to comment out the APP_ERROR_HANDLER() in the uart communication error event, and see if that changes the behavior.&nbsp;</p> <p>The issue is that the UART&#39;s RX line is floating, and when the pin floats between 1 and 0 the UART believe that someone has tried to send a message, but it was corrupted.</p> <p></p> <p>Best regards,</p> <p>Edvin</p><div style="clear:both;"></div>